Best signaling devices from the searcher’s point of view - update

[Dan]

Oh great! You understand triangulation.

There are at least 4 GPS overhead at any point on earth with GPS coverage. This means that there are lots of GPS satellites in total. Your PLB needs to see 3 GPS satellites in order to triangulate your position. According to the NOAA presentation Pg. 23, "Minimum of 3 satellites needed to compute locations. Additional satellites improve accuracy."


Lets try and keep this simple. Think of transmitting as speaking. Then think of receiving as hearing.

Your PLB1 user manual says, "Warning : As testing the GPS receiver expends significant amounts of battery energy do not test the gps operation more than oncea year."

I don't think your PLB transmits to the GPS satellites. I think the GPS satellites transmit a signal that your PLB has to receive. Your PLB1 manual refers to the GPS receiver.

Your PLB receives (hears) transmissions from GPS satellites. Based on this, it calculates your GPS position by triangulation. Your GPS position is then transmitted by your PLB to LEOSAR/GEOSAR on 406MHz.


Your PLB1 manual says:
"GPS Receiver (rescueME PLB1 only)
Satellites Tracked. . . . . . . . . . . . . . . . . . . . . . . . . . .66 Channel"

Wikipedia says that there were 2 frequencies used in the original design of GPS. Your PLB1 tracks 66 channels. If each channel is tuned to one frequency, there could be a number of different frequencies currently used by GPS satellites. I don't know what those frequencies are.

So let me get this straight:
PLB1 built-in GPS receiver collects its latitude & longitude data from at least 3 GPS satellites orbiting about 13000 miles above the earth and transmit the recently obtained GPS position together with my PLB1 Unique Identifier Number & the radiotelephony locator beacon sound (unique PLB alert sound) to LEOSAR & GEOSAR satellites at 406 MHz frequency. The LEOSAR & GEOSAR satellites then transfer the beacon's signal to their respective ground control stations. The ground stations process the signals (which include calling our emergency contact for verification that it is not a false alert) and forward the data, including approximate location, to a national authority. The national authority forwards the data to a rescue authority. The rescue authority uses its own receiving equipment afterwards to locate the beacon and commence its own rescue operations to find us. Is that correct?

There are so many YouTube videos on How GPS receiver works. Trace Dominguez of DNews is very animated & funny to keep me interested in “how to find pizza” & able to get the GPS concept drilled through my thick skull

 

[CWK]

So let me get this straight:
PLB1 built-in GPS receiver collects its latitude & longitude data from at least 3 GPS satellites orbiting about 13000 miles above the earth and transmit the recently obtained GPS position together with my PLB1 Unique Identifier Number & the radiotelephony locator beacon sound (unique PLB alert sound) to LEOSAR & GEOSAR satellites at 406 MHz frequency. The LEOSAR & GEOSAR satellites then transfer the beacon's signal to their respective ground control stations. The ground stations process the signals (which include calling our emergency contact for verification that it is not a false alert) and forward the data, including approximate location, to a national authority. The national authority forwards the data to a rescue authority. The rescue authority uses its own receiving equipment afterwards to locate the beacon and commence its own rescue operations to find us. Is that correct?

There are so many YouTube videos on How GPS receiver works. Trace Dominguez of DNews is very animated & funny to keep me interested in “how to find pizza” & able to get the GPS concept drilled through my thick skull

Just keep watching.

 

[tcpip95]

This is a very good video on what happens when you push the button. Keeps it simple, but explains it from pushing the button to getting rescued.

 

[Dan]

This is a very good video on what happens when you push the button. Keeps it simple, but explains it from pushing the button to getting rescued.

It sure is. @Dogbowl posted it in page 6 post #58, but I like to view it again.

 

[tcpip95]

LOL.... oops. sorry 'bout that.

 

[CWK]

So let me get this straight:
PLB1 built-in GPS receiver collects its latitude & longitude data from at least 3 GPS satellites orbiting about 13000 miles above the earth and transmit the recently obtained GPS position together with my PLB1 Unique Identifier Number & the radiotelephony locator beacon sound (unique PLB alert sound) to LEOSAR & GEOSAR satellites at 406 MHz frequency

The GPS satellites do not know you exist. They (the GPS satellites) do, however, know their own GPS position and the time. This is the info that they transmit out to all and sundry. When your PLB has received these messages from at least 3 GPS satellites, it (your PLB) calculates your GPS location and then sends it to the SAR satellites.

 

[CWK]

I'll ask Ryan about the MRG frequency of GPS acquisition & transmission later.

How does the Nautilus work out GPS position?

 

[Dan]

Just keep watching.

The more I watch those GPS & PLB videos & read about the detail ins & outs of the signals, how much power required to track, lock in the satellites, & calculate the latitude & longitude of the incident, the more I convince that during a dire situation, once I turn the PLB ON, I'd need to keep it ON for the rest of its battery life.

I read in some ski forum / PLB FAQ that turning PLB on / off could, not only wasting battery life, but also could result in the MCC (NOAA) to consider the signal as false alert or hoax. That would be the furthest thing you want to get from a device of the last resort.

 

[CWK]

Since I expect 30 Hours from my PLB in warm water, it will just get turned on until the battery dies or SAR turns up.

Don't test the GPS receiver too often as that consumes loads of battery. Note that if the GPS receiver does not work, LEOSAR can still work out your location through Doppler shifts.

 

[Dan]

How does the Nautilus work out GPS position?

Still waiting reply from Ryan. He said a couple days ago that he would need to check that info with the Nautilus Lifeline engineers and would get back to me ASAP. It's now weekend, so I won't expect a reply until Monday at the earliest.